Homestead Cave, a paleontological site located in a low-elevation arid setting in the northern Bonneville Basin of northcentral Utah, documents the local extinction of Neotoma cinerea during the Middle Holocene. N. cinerea is present there today, and the Homestead Cave record suggests that recolonization likely occurred sometime prior to 1,000 years ago. This history supports the view (forwarded by T. E. Lawlor) that cross-valley dispersal by mammals that generally are most abundant in cooler and moister (and therefore higher elevation) parts of the Great Basin is still occurring, showing that Brown's model of Great Basin montane mammalian biogeography is incorrect. These dispersal patterns suggest that conservation efforts directed toward montane mammals in the Great Basin must include low-elevation access corridors to mountain masses.